“What Mr. Cavendish suggests is quite impossible. Any doctor would tell you the same. Strychnine is, in a certain sense, a cumulative poison, but it would be quite impossible for it to result in sudden death in this way. There would have to be a long period of chronic symptoms which would at once have attracted my attention. The whole thing is absurd.”

“And the second suggestion? That Mrs. Inglethorp may have inadvertently taken an overdose?”

“Three, or even four doses, would not have resulted in death. Mrs. Inglethorp always had an extra large amount of medicine made up at a time, as she dealt with Coot’s, the Cash Chemists in Tadminster. She would have had to take very nearly the whole bottle to account for the amount of strychnine found at the postmortem.”